Preparation of polyurethane foam using arylenedicarbamic acid ester catalyst



United States Etcnt PREPARATION OF POLYURETHANE FOAM USING ARYLENEDICARBAMIC ACID ESTER CATALYST Bernard Taub, Buffalo, N.Y., assignor to Allied Chemical Corporation, a corporation of New York No Drawing. Filed Feb. 26, 1958, Ser. No. 717,566 6 Claims. (Cl. 260-'-2.5)

This invention relates to polyurethane foams and more particularly refers to a new and improved. catalyst for effecting the reaction of an alkyd resin with an isocyanate for the production of cellular plastic materials.

Polyurethane foams prepared by reaction of polyisocyanates with alkyd resins are commercial products Well known in the art described in German Plastics Practice, by De Bell et al., 1946, pages 316 and 463-465 and in the literature and patent references. Conventional practice in the production of the polyurethane foams is to employ known amine catalysts such as N-methyl morpholine, dimethylcyclohexylamine and triethylarnine. Unfortunately, foams produced by the use of conventional catalysts have a characteristic amine odor which is generally obnoxious to persons and depreciates the sales value and appeal of the foam product.

An object of the present invention is to provide a method for producing odorless polyurethane foams by reacting a polyester and a polyisocyanate. Another object of the invention is to provide new and novel catalysts adapted for use in the production of cellular polyurethanes by reaction of polyisocyanates with alkyd resins. Other objects and advantages will be apparent from the following description.

The new catalysts are arylenedicarbamic acid esters of the general formula:

Nalkylene-OCNHAr-NHCOAlkylene-N R c") H R wherein R and R" are lower alkyl radicals with from 1 to carbon atoms, R and R together with the attached N atom form part of a heterocyclic ring, alkylene means a divalent non-cyclic saturated hydrocarbon radical having the general formula C H and Ar is an aromatic ring system containing at least ten nuclear carbon atoms and preferably not more than twenty nuclear carbon atoms.

Such diurethane compounds are obtained by the reaction of two mols of a monohydric amino alcohol of the general formula N-alkylene-OH where R and R" are lower alkyl radicals with from 1 to 5 carbon atoms, R and R" together with the attached N atom form part of a heterocyclic ring system, alkylene means a divalent non-cyclic saturated hydrocarbon radical having the general formula C H with one mol of an arylene diisocyanate in which the arylene radical consists of an aromatic ring system Ar containing at least ten nuclear carbon atoms and preferably not more than twenty nuclear carbon atoms; The aromatic ring system contains two or more benzene rings, which may be fused together, e.g. naphthalene, or joined by a single bond through n'ng C atoms, e.g. biphenyl, or joined through a divalent radical or atom such as methylene, O-, S-, etc. The arylene radical Ar may contain nuclear substituents such as lower alkyl, alkoxy, halogen, or other groups that are not reactive with isocyanate groups.

areas Patented Sept. 26, 1961 For the purposes of the present invention a wide variety of monohydric alcohols having a tertiary amino group may be employed in the reaction with the arylene diisocyanate. Suitable amino alcohols are preferably those having a primary hydroxyl group such as 2-(dialkylamino)-ethanols in which the alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, etc.; Z-aminoethanols in which the amino nitrogen atom is part of a heterocyclic ring system, as in piperidino-, morpholino-, pyrrolidinocompounds; and similar tertiary amino compounds derived from B-amino-propanol, 3-amino-2-methyl-propanol, 3-amino3-methyl-propanol, 4-aminobutanol, etc. Amino alcohols having a secondary hydroxyl group and a tertiary amino group of the type illustrated above with Z-amino-ethanols may also be utilized, such as 3-(tertia1y armino)-isopropanol, 4-(tertiaryamino)-2-butanol, 4-tertiaryamino)-3-methy1-2-butanol, etc. The preferred alcohols are 2-piperidinoethanol, 2-pyrrolidinoethanol, di-

ethylaminoethanol, dipropylarninoethanol and 4 morpholineethanol.

The organic diisocyanate employed in the preparation of these new diurethane compounds is an aromatic diisocyanate containing at least ten nuclear carbon atoms, and preferably not more than twenty carbon atoms in the ring system. Suitable diisocyanates include the following, 1,5- naphthylene diisocyanate, 4,4-biphenylene diisocyanate, 3,3-dimethy1 4,4 biphenylene diisocyanate, 3,3'-dimethoxy-4,4-biphenylene diisocyanate, 3-phenyl-4,4'-biphenylene diisocyanate and 1,5-naphthylene diisocyanate.

'The reaction of the arylene diisocyanate with the amino alcohol is preferably carried out in the presence of an inert organic solvent such as diethyl ether or benzene. To avoid lossof diisocyanate and to avoid the formation of contaminants such as ureas, the solvent should be anhydrous. By virtue of their two tertiary amino groups the novel arylenedicarbamic acid esters can readily be converted to acid addition salts, e.g. acetate, hydrochlorides and phosphates, or quaternary ammonium salts, e.g. methiodides, which are water soluble. The organic acid addition salts, e.g. acetates, may be employed as catalysts per se. The inorganic acid addition salts, such as the hydrochlorides, are preferably used in conjunction with an inorganic base, which will generate at least part of the free diurethane base. When no water as such is added, a hydrated inorganic base, e.g.

is employed, which will release water when the mixture is heated.

The foams may be prepared in the usual manner by admixing and introducing into a mold the components composed of a polyester, diisocyanate, water in the presence of a small amount, about 0.5-10% preferably l-3% based on the weight of polyester, of the new arylenedicarbamic acid ester as catalyst. Ordinarily the polyisocyanate being admixed is in an amount of at least 20%, preferably 40-80% by weight of the polyester. The water should be in an amount enough to react with the isocyanate to liberate sufiicient gas to produce a foam of'the desired physical characteristics. From 0.5 to 10% water based on the weight of isocyanate will genthe lower the density of the foam. The mixing of the 3 4 constituents may be carried out at an elevated tempera- Example 1 ture or under atmospheric conditions. To 125 parts di h l thane4,4'-diisogyanate dis- In the preparation of polyurethane foams 1t isde solved in 100 parts anhydrous diethyl ether there is added to employ a dlspersmg agent, deslrably a P' dropwise over half an hour, with constant agitation a persing agent, to assist in the intimate mixlng of the 5 Solution of 123 parts Lbiperiainbethanol i 0 part3 l'eactantsanhydrous diethyl ether. The addition is completed in The Pfeffiffed emulsifiers are Qf the 1101140111; type half an hour and the reaction mixture is then warmed S as a mOIlOethel" of a Polyethylene glycol with an to reflux temperature for a period of six hours. The solalkyl Phenol, blends of P 211601101 cafboxylic add vent is removed by distillation andthe resulting diurethane esters and l soluble sulfonate (W p y y r m is recrystallized from hot carbon tetrachloride in 85% 6 glycol Ficinoleate p Sorbitan yield. This compound has a melting point of 125 C.

monolaurate (Span and poloxy alkylene derivaand has the formula H oHroHT-m-o-irQ-om-ON-o-o-on.on, I ll II I N O O, N\ C \CH1 (llfis (3H1 (3H1 H: CH2 CH1 CH1 0 2 tives of sorbitan monolaurate (cg. Tween. .20 and The water soluble dihydrochloride may be. obtained by Tween 80). Anionic emulsifiers such as sodium dioctyl treating an anhydrous ethyl acetate solution of the disulfosuccinate may also be used. In general the amount urethane with anhydrous hydrogen chloride gas. of emulsifier required does not exceed 10% based on the polyester Example 2 lfrepolymers may be prepared by first reacting the di- In the process of Example 1 in place of Z-piperidinoisocyanate with the polyester in the absence of water to ethanol there is used an ether solution of 13.1 parts of form a prepolymer. In the preparation of polyurethane o 4-morpholineethanol whereby the corresponding bisfoam, the new arylenedicarbamic acid ester catalyst and morpholinoethyl diurethane is produced. It has the fordispersing agent may first be dissolved in water and this mula N (Ji s \CH: (iln'z on H CH CH solution added to the prepolymer, preferably at room and can be converted to the water soluble dihydrochloride temperature, and the resultant mixture agitated vigorously salt by treatment with anhydrous hydrogen chloride gas. fora short time, less than a minute, and then poured into a mold. Foaming will start immediately. The rate of foaming may be increased considerably by heating the In the process of Example 1 there is used an ether Example 3' prepolymer prior to addition of catalyst mixture. solution (IOOparts ether) of 11.5 parts of 2-pyrrolidino- The polyester may be linear or branched chain and is ethanol to react with the diphenylmethane-4,4-dusocyderived from polycarboxylic organic acids and polyhyanate. The product has the formula:

CHz-CHg H /CH5CH2 NCH:|CHg-0--C- C -CHrC NfiO-CHzCHr-N\ CHr-Cz i 0 CHz-CH: dric alcohols. Suitable linear polyesters are those pre- Example 4 pared by the reaction of dicarboxylic organic acids such 13.2 parts of 3,3'-dimethyl-4,4' biphenylene diisocyas. adipic, fumaric, maleic, malic, phthalic, sebac ic with anate are dissolved in 100 parts anhydrous diethyl ether polyhydric alcohols such as ethylene glycol, diethylene and stirred vigorously during a dropwise additlon (half glycol, propylene glycol, glycerol and trimethylolpropane. an hour} of a Solution of Parts of dielhylamiflo- Suitable polyisocyanates include hexamethylene diisoethanol 100 P anhydrous ether- The ct cyanate, cyclohexyl l,4 diisocyanate tolylene diisocy mixture is refluxedfor six hours and the solvent removed 0 r anates, diphenylmethane-4,4'-diisocyanate substituted gi i g to give a ii g (96% p' diphenyl methane-4,4'-diisocyanates, naphthalene diisoe dmret an? r-ecrystal om carbon tetrachloride cyanates and others. The amount of polyisocyanate used has a meltmg pomt of and analyzesshould be such that there is an excess of isocyanate groups 35 m Cm, over the reactive hydrogen atoms contained in the polyester so as to react completely with the polyester. To 0-- p 07. 32 67.47 accomplish this the polyisocyanate should be generally 5 I 313 used in an amount of at least 20% by weight of the polyester. It corresponds with the formula:

011mg, IE! CH; CH; I i CHLCYHJ N.on,oHPo- +NO-n+ Tq -cn,cmn CHa.CHz 0, 0 CHLCHe Thefollowing examples illustrate the present invention, lt can-be-dissolved in a suitable anhydrous solvent for mtwh ch parts given are by weight. 7 conversion to the dihydrochloride salt.

ether solution (100 parts anhydrous ether) of 12.9 parts 3,001,955 5, 6 I Example Example 9 In the process of Example 4 there is used an ether 100 parts linear polyester (Paraplex Ill-148, diethy'b solution (100 parts ether) of 14.5 parts of dipropylaminoene glycol adipate, hydroxyl number 55-65), 2.5 parts ethanol to react with 13.2 parts of 3,3'-dimethyl-4,4-biwater, 1.0 part emulsifying agent (Witco 77-86, blend phenylene diisocyanate. The recrystallized base has a of poly alcohol carboxylic acid esters and oil soluble melting point of 82-3" and analyzes N of 10.11% sulfouates) and 2.0 parts of catalyst (the diurethane base (calc. N=10.15%) corresponding to the formula: prepared as in Example 4 above), were mixed with high 2 CH8 CH i t i NHrCHa-O(" N Nfi--OCH2CH2N\ (I) Q CH: O O C CH1v OH! H: H: CH1

H: CH: a Hr Example 6 speed agitation. Then 39 parts by weight of tolylene di- In the process of Example 4 the ether solution of diisocyanate (80% 2,4-isomer and 2,6-isomer) were ethylaminoethanol may be replaced by a solution of 13.1 20 added. The resulting mixture was agitated for 15-20' parts of 4-morpholineethanol in 100 parts ether and the seconds and poured into a mold open at its top. The

corresponding bis-morpholinoethyl diurethane is obtained time required for the foam to reach the top of the mold in high yield. The base has a melting point of 164-5 was 4 /2 minutes. The foam structure was essentially and analyzes completely maintained until a permanent set foam was produced. The resultant polyurethane foam was odor- ,Found Cam less, i.e. devoid of the characteristic amine odor of con ventional amine catalyst. i" 31?? 3:23 Example 10 The conditions of operation in this example were the It corresponds to the formula: same as in Example 9 except that the catalyst employed CH3 on, i /N.CH2CHa---O-fiN -Nfi0-C1LOH7N\ (fHa CHz. O O CH5 CH1 CH2 CH2 CH2 CH:

Example 7 40 was the bismorpholinoethyl diurethane base prepared as in Example 2 above. The principal dilference was in the time required for the foam to attain maximum height, 3 /6 minutes as compared to 4 /2 minutes when employing the catalyst of Example 9. The polyurethane foam of Example 10, like that of Example 9, was odorless.

In the process of Example 4 there may be used an of 2-piperidinoethanol to react with 13.2 parts of 3,3-dimethyl-4,4-biphenylene diisocyanate. The diurethane base has a melting point of 250 and analyzes C For purposes of comparison a control test was run in Fmmd which the conditions were the same as Example 9 except 0 68 so 68 97 that no catalyst was employed. In the control experirrj' 110 3105 0 ment using no catalyst the time required forthe foam to 1061 1973 reach the top of the mold was appreciably longer, '10

minutes, and the foam collapsed soon after rising. corresponding to the formula 7 CH3 CH3 i i NcH1cH,-00N N-C-OCH:CHz-N H g C s CH: O O (I) a CH1 CH2 B2 C5: /CH2 0H, CH2

The resulting diurethane may be converted to the water v soluble hydrochloride salt. Although certain preferred embodiments of the inven- Example tion have been disclosed for purpose of illustration, it will be evident that various changes and modifications In the process of Example4 the diethylaminoethanol may be made therein without departing from the scope is replaced by 11.5 parts of 2-pyrrolidinoethanol to proand spirit of the invention. duce the corresponding bis-pyrrolidinoethyl diurethane I claim:

having a melting point of 138-140", and the formula 1. In a process for the production of polyurethane CH: CH3

7* foams involving the reaction of a polyester prepared foams involving the reaction of a polyester prepared from from pqlyearboxylic organic acids and polyhydric, alcopolycarboxylic organic acids and polyhydric alcohols and hols and an organic polyisocyanate in an amount of at an organicpolyisocyanate in an amount of at least 20% least 20% by weight of the polyester, and water, the by Weight of the polyester, and water, the improvement improvement which comprises effecting said reaction in which comprises eifecting said reaction in the presence;

the presence of an arylenedicarbamic acid ester catalyst of an arylenedicarbamic acid ester catalyst of the formula:

2 r $H,CHgOfiN -CHIC Nfi-OCHAEHI /N\ 0 o N\ (1H2 (3H2 C (EH3 CE: /CH2 4151 CH: 0 o

of the formula:

R RI

4. In a process for the production of polyurethane R II I! I foams involving the reaction of a polyester prepared h O O R from polycarboxylic organic acids and polyhydric alcow erem B, hols and an organic polyisocyanate in an amount of at least 20% by weight of the polyester, and water, the improvement which comprises effecting said reaction in R" the presence of an arylenedicarbamic acid ester catalyst is selected from the class in which R and R" are lower of the formula:

CH3 CH3 /N CHICHTO-HCN N("3O CHCH17N\ 0H, CH 0 0 CH: CH:

CH: H: H: CH1

CH1 OH; H: CH2 alkyl radicals with from 1 to 5 carbon atoms, and a 6. In a process for the production polyurethane foams heterocyclic group in which R and R together with involving the reaction of'a polyester prepared from polythe attached N atom form part of a heterocyclic ring, carboxylic organic acids and polyhydric. alcohols and an alkylene means a divalent non-cyclic saturated hydroorganic polyisocyanate in an amount of at least 20% by carbon radical having the general formula C H in which weight of the polyester, and water, the improvement 71 represents an integer greater than 1 and less than 5, which comprises effecting said reaction in the presence of and Ar is an aromatic ring system containing at least ten an arylenedicarbamic acid ester catalyst of the formula:

nuclear carbon atomsand not more than twenty nuclear 6. In a process for the production ofpolyurethane carbon atoms. foams involving the reaction of a polyester prepared 2. In a process for the production of polyurethane from polycarboxylic organic acids and polyhydn'c alco-.

foams involving the reaction of a polyester prepared hols and an organic polyisocyanate in an amount of at from polycarboxylic organic acids and polyhydric alcoleast 20% by weight of the polyester, and water, the imhols and an organic polyisocyanate in an amount of at provement which comprises etfecting said reaction in the least 20% by weight of the polyester, and water, the presence of an arylenedicarbamic acid ester catalyst of improvement which comprises effecting said reaction in the formula:

CHrCHz H" H CHFCH CHz-CH: Q CHE-CH- th esenc of an lened' arbamic a d este tal st ofetgformgla: my 16 cl r ca y References Cited in the file of this patent CH; CH, UNITED STATES PATENTS I 2,683,728 Mastin et a1. July 13, 1954 E fi- OO 'fi' E 2,877,192 Burkus Mar. 10, 1959 N 0 2,878,279 Schmid et al. Mar. 17-, 1959 CH: CH: (EH: 0

E CH, CH F REIGN PATENTS 0 754,502 Great Britain Aug. 8, 1956 3. In a process for the production of polyurethane 1135863 France 1956 

1. IN A PROCESS FOR THE PRODUCTION OF POLYURETHANE FOAMS INVOLVING THE REACTION OF A POLYESTER PREPARED FROM POLYCARBOXYLIC ORGANIC ACIDS AND POLYHYDRIC ALCOHOLS AND AN ORGANIC POLYISOCYANATE IN AN AMOUNT OF AT LEAST 20% BY WEIGHT OF THE POLYESTER, AND WATER, THE IMPROVEMENT WHICH COMPRISES EFFECTING SAID REACTION IN THE PRESENCE OF AN ARYLENEDICARBAMIC ACID ESTER CATALYST OF THE FORMULA: 